COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pratt and Whitney Piston Engines AD/PW-P/12 Operating Restrictions - Placarding NK Applicability: R2000 series installed in Douglas DC4 aeroplanes and fitted with Hamilton Standard 23E50/6507-0 propellers. Requirement: 1. Avoid steady operation of the engines in the ranges 1550 to 1750 r.p.m. in flight and 1550 to 1800 r.p.m. during ground running when the propeller blades are off the low pitch stops. 2. The R.P.M. indicators in aeroplanes affected shall be marked with a suitable red sector over the 1550 to 1750 r.p.m. range. 3. Remove the existing placard covering the 1600 to 1700 r.p.m. range and install a new placard setting out the restrictions specified in paragraph 1. Note: If desired the placard required by paragraph 3 may incorporate the limitation on the 2310 to 2510 r.p.m. range required by ANO AD/PW-P/8. or FAA AD 62-26-1. Compliance: Forthwith.